When the immune system responds to an antigen various cells of the immune system are activated. These activated cells synthesize a series of lymphokines which then in turn regulate the activation, proliferation and differentiation of further cells of the immune system. The T lymphocytes play a central role in this process the growth of which is controlled by a specific factor, interleukin 2 (IL-2). IL-2 is a lymphokine of 133 amino acids and exerts its growth-promoting properties via binding to specific receptors on the cell surface.
The interleukin 2 receptor (IL-2R) is present in three forms which differ in their-composition and in their affinity to the ligand. The low-affinity IL-2R (Kd=10xe2x88x928 M), which is also denoted xcex1 chain, light (L) chain, p55 molecule and in humans is also designated CD25 or Tac antigen, is a glycoprotein of 55 kDa molecular weight. The genes for the xcex1 chain of the murine, bovine and human IL-2R have been cloned and the amino acid sequences of their protein products have been determined (Miller et al., J. Immunol. 134 (1985) 4212-4217; Nikaido et al., Nature 311 (1984) 631; Weinberg et al., Immunology 63 (1988), 603).
The medium affinity IL-2R (Kd=10xe2x88x929 M), which is also denoted xcex2 chain, heavy (H) chain or p75 molecule, is a glycoprotein with a molecular weight of 70 to 75 kDa in the mouse and humans (Tsudo et al., Proc. Natl. Acad. Sci. USA 83 (1986), 9694; Sharon et al., J. Exp. Med. 167 (1988), 1265).
The high affinity IL-2R (Kd=10xe2x88x9211 M) is a heterodimer which is composed of non-covalently bound xcex1 and xcex2 chains (Wang and Smith, J. Exp. Med. 166 (1987), 1156; Waldman, J. Nat. Cancer Institute 81 (1989) 915).
Monoclonal antibodies against the xcex1 chain as well as against the xcex2 chain of the human IL-2 receptor have been isolated and they have been demonstrated to have an immunosuppressive action in vitro as well as in vivo (Sakagami et al., Transplantation Proceedings Vol. XIX. (1) (1987), 586-590; Kupiec-Weglinski et al., Proc. Natl. Acad. Sci. USA 83 (1986), 2624-2627; Mouzaki et al., Eur. J. Immunol. 17 (1987), 335-341; Olive et al., Eur. J. Immunol. 16 (1986), 611-616; Friend et al., Transplantation Proceedings, Vol. XIX (1987), 4317-4418; Soulillou et al., Lancet, Jun. 13, (1987), 1339-1342; Kupiec-Weglinski et al., Eur. J. Immunol. 17 (1987), 313-319).
Monoclonal antibodies against IL-2R have a high potential for immunosuppressive therapy, in particular for treating graft rejections, adult T cell leukemia and autoimmune diseases such as e.g. rheumatoid arthritis.
It has, however, been shown that the in vivo administration of monoclonal antibodies of animal origin in humans is limited since they are recognized as being foreign and this leads to an immune reaction against the administered antibodies. This immune reaction can be reduced by using so-called chimeric or humanized antibodies. Chimeric antibodies are antibodies in which the constant domains of animal origin (e.g. the mouse) have been replaced by a human constant domain. Humanized antibodies are human antibodies of which only the antigen binding sites of the variable region (the CDR or hypervariable regions) are of animal origin (Verhoeyen and Riechmann, BioEssays 8 (1988), 74-78).
However, even when administering chimerized or humanized antibodies an undesired immune reaction of the patient can be observed in some cases at higher doses, which is caused by the production of anti-idiotypic antibodies.
The object of the present invention is therefore to provide antibodies which are effective in an immunosuppressive therapy and which can be used in substantially lower doses than previously known antibodies.
The present invention concerns an antibody composition which inhibits the binding of interleukin 2 to its high affinity receptor and contains
(1) monoclonal antibodies against the xcex1 chain of the interleukin 2 receptor and
(2) monoclonal antibodies against the xcex2 chain of the interleukin 2 receptor.
Surprisingly the combined use of monoclonal antibodies against the xcex1 chain as well as against the xcex2 chain of the IL-2 receptor in vitro leads to synergistic effects and thus the antibody composition according to the present invention results in a stronger inhibition of the IL-2 induced proliferation of human peripheral blood lymphocytes than when one of the two antibodies is used alone at the corresponding concentration.
An antibody composition according to the present invention preferably contains
(1) 1 to 99% in relation to the total antibody amount of monoclonal antibodies against the xcex1 chain of the interleukin 2 receptor and
(2) 99 to 1% in relation to the total antibody amount of monoclonal antibodies against the xcex2 chain of the interleukin 2 receptor.
The composition preferably contains 4 to 96% in relation to the total antibody amount monoclonal antibodies against the xcex1 chain of the interleukin 2 receptor and 96 to 4% in relation to the total antibody amount of monoclonal antibodies against the xcex2 chain of the interleukin 2 receptor. When the antibody ratio is 4:96 or 96:4, one already finds a five-fold reduction in the total amount of antibody compared to the use of only one monoclonal antibody against the xcex1 or the xcex2 chain.
The composition according to the present invention is particularly preferred when it contains aproximately equal amounts (1) of monoclonal antibodies against the xcex1 chain of the interleukin 2 receptor and (2) monoclonal antibodies against the xcex2 chain of the interleukin 2 receptor. At an equimolar ratio of antibodies it is found that the total concentration of monoclonal antibodies required for a 60 to 70% inhibition of the IL-2 action is reduced fifteen-fold.
The composition according to the present invention preferably contains an antibody against the xcex1 chain which by itself already causes an inhibition of the interleukin 2 binding. It is also preferred that the composition according to the present invention contains an antibody against the xcex2 chain which by itself already causes an inhibition of the interleukin 2 binding. A composition according to the present invention is particularly preferred when it contains in each case an antibody against the xcex1 chain and an antibody against the xcex2 chain each of which alone already causes an inhibition of the interleukin 2 binding.
The antibody 3G10/179 (ECACC 90071905) which was deposited at the European Collection of Animal Cell Cultures, PHLS Centre for Applied Microbiology and Research Portion Down, Salisbury, U.K. on Jul. 19, 1990, is preferably used as the antibody against the xcex1 chain which is present in the composition according to the present invention. However, other antibodies against the xcex1 chain of interleukin 2 are also suitable in particular when they by themselves already cause an inhibition of the interleukin 2 binding. The antibodies C68/41 (ECACC 90090704) which was deposited at the European Collection of Animal Cell Cultures, PHLS Centre for Applied Microbiology and Research Portion Down, Salisbury, U.K. on Sep. 7, 1990, and A23A41 (DSM ACC2015) xcex2 which was deposited at DSM-Deutsche Sammlung von Mikroorganismen Und Zellkulturen GmbH, Mascheroder Weg 1B, D-3300 Braunschweig on Jul. 30, 1991, are particularly suitable as the antibody against the xcex2 chain of the interleukin 2 receptor as are, antibodies known from the literature such as the Mik/xcex21 antibody (Tsudo et al., Proc. Natl. Acad. Sci. USA 86 (1989), 1982-1986; Takeshita et al., J. Exp. Med. 169 (1989), 1323-1332).
The composition according to the present invention can also contain a covalent coupling product of a monoclonal antibody against the xcex1 chain and a monoclonal antibody against the xcex2 chain of the interleukin 2 receptor.
The composition according to the present invention preferably contains one or several chimerized antibodies with human constant domains or humanized antibodies in which the non-hypervariable parts of the variable domain are also replaced by the corresponding human regions. In this case one preferably uses chimerized antibodies whose variable domains have been isolated by new methods described in DE 40 33 120 and in a further corresponding application.
The present invention also encompasses a pharmaceutical agent which contains an antibody composition according to the present invention as well as, if desired, the usual pharmaceutical carrier substances, fillers, auxiliary agents and additives and a process for the production of such a pharmaceutical agent in particular for the immunosuppressive therapy of lymphoproliferative diseases, autoimmune diseases, graft rejections or other disorders in the organism in which T cell proliferation has to be at least temporarily suppressed. The invention furthermore encompasses the use of such a pharmaceutical agent for immunosuppressive therapy.
Finally the invention also encompasses a method for treating disorders of the immune system, in particular for immunosuppression, in which a pharmaceutical agent according to the present invention is administered.
The cell lines which produce the aforementioned antibodies were deposited at the European Collection of Animal Cell Cultures (ECACC), Porton Down (GB) or the xe2x80x9cDeutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSM), Mascheroder Weg 1b, D-3300 Braunschweigxe2x80x9d and assigned the depository numbers:
3G10/179: ECACC 90071905 (Date of deposit: 19.07.1990)
C68/41: ECACC 90090704 (Date of deposit: 07.09.1990)
A23A41: DSM ACC2015 (Date of deposit: 30.07.1991)
The sequences of the variable regions of the antibody A23A41 are described in the attached sequence protocols. Suitable constant regions (murine or human) for this antibody are described in: Sequences of proteins of immunological interest; E. Kabat, T. Wu, M. Reid-Miller, H. Perry and K. Gottesman, US Department of Health and Human Services, 1987, p. 282-325.
It is intended to also elucidate the present invention by the following example in conjunction with the sequence protocols.
SEQ ID NO.1 shows the nucleotide sequence and amino acid sequence of the variable region of the light chain of the anti-IL2Rxcex2 antibody A23A41.
SEQ ID NO. 2 shows the nucleotide sequence and amino acid sequence of the variable region of the heavy chain of the anti-IL2Rxcex2 antibody A23A41.